Classical non-active power factor corrected (PFC) ballasts use small capacitors and an output waveform that follows the input waveform to achieve acceptable power factor. This can lead to problems in the starting of a self oscillating resonant circuit. A ballast inverter in such ballasts typically only starts up on one of two input half cycles, which causes a delay in starting at the minimum and at its worst case of skipping starting of every other half cycle, causes the ballast to operate at half power. That is, for non-active PFC ballasts, there is no constant direct current (DC) bus feeding the resonant inverter in the ballast, and therefore the ballast needs to start on every one of the rectified positive and negative phases of the alternating current (AC) input provided to the inverter.
A ballast is an electrical device which is used to provide power to a load, such as an electrical lamp, and to regulate the current provided to the load. For fluorescent lamps, the ballast provides high voltage to start a lamp by ionizing sufficient plasma (vapor) for the arc to be sustained and to grow. Once the arc is established, the ballast allows the lamp to continue to operate by providing proper controlled current flow to the lamp. The term driver is also used to describe this type of power supply that regulates power to loads such as LEDs, OLEDs, CFLs, and many other non lighting loads.
Accordingly, there is an unmet need in the art for systems and methods that facilitate reliably starting a ballast circuit regardless of input half cycle, and for overcoming the deficiencies noted above.